I don't have pain in my knees and I haven't my whole time in Vietnam. That's five months.
For the last few years, I've gotten sore knees every few months. Stairs, chairs and toilets were my main challenges. I couldn't squat to sit down or put all my weight on one leg to do stairs. After a few days or a week or two the pain would completely subside.
I do a lot of walking and a lot of stairs here and I have had no problems with my knees. You may or may not know that we've started running, too. Even with that, no problems.
I am really feeling that there are many, many people on their knees for us.
My knees (don't) feel it.